CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balances at Dec. 31, 2014	$ 521,751		$ 25,045	$ 194,647	$ 302,882	$ (823)
Net income	11,225		0	0	11,225	0
Other comprehensive loss, net of tax	2,969		0	0	0	2,969
Common stock dividends - $0.24 and $0.22 per share at March 31, 2016 and 2015, respectively	(5,561)		0	0	(5,561)	0
Stock compensation expense, Adjustments to Additional Paid in Capital, Requisite Service Period Recognition, Total	422		0	422	0	0
Common stock issued pursuant to:
Stock option plan - 21,694 and 5,752 shares at March 31, 2016 and 2015, respectively	74		6	68	0	0
Employee stock purchase plan - 6,937 and 6,663 shares at March 31, 2016 and 2015, respectively	169		6	163	0	0
Restricted stock - 15,162 and 27,945 shares at March 31, 2016 and 2015, respectively	(243)		28	(271)	0	0
Purchase of treasury shares - 512,459 and 351,369 shares at March 31, 2016 and 2015, respectively	(9,038)	$ (351)		(8,687)	0	0
Balances at Mar. 31, 2015	521,768		24,734	186,342	308,546	2,146
Balances at Dec. 31, 2015	524,427		24,296	175,588	325,840	(1,297)
Net income	10,813		0	0	10,813	0
Other comprehensive loss, net of tax	5,530		0	0	0	5,530
Common stock dividends - $0.24 and $0.22 per share at March 31, 2016 and 2015, respectively	(5,843)		0	0	(5,843)	0
Stock compensation expense, Adjustments to Additional Paid in Capital, Requisite Service Period Recognition, Total	477		0	477	0	0
Common stock issued pursuant to:
Stock option plan - 21,694 and 5,752 shares at March 31, 2016 and 2015, respectively	285		21	264	0	0
Employee stock purchase plan - 6,937 and 6,663 shares at March 31, 2016 and 2015, respectively	157		7	150	0	0
Restricted stock - 15,162 and 27,945 shares at March 31, 2016 and 2015, respectively	(181)		15	(196)	0	0
Purchase of treasury shares - 512,459 and 351,369 shares at March 31, 2016 and 2015, respectively	(13,273)	$ (512)		(12,761)	0	0
Balances at Mar. 31, 2016	$ 522,392		$ 23,827	$ 163,522	$ 330,810	$ 4,233